1. Field of the Invention
The process of the present invention relates generally to hydrometallurgical chemical leaching, as classified in Class 75, subclass 101R; and in one preferred embodiment relates to the treating of a mixture to obtain an antimony-containing compound as classified in Class 423, subclass 87.
2. The Prior Art
A number of sulfide mineral ore bodies exist which possess a considerable amount of antimony values. These antimony values may be existent in several forms, including tetrahedrite and stibnite. Often they exist in association with other mineral values, such as chalcopyrite. While no processes are known which deal directly with recovering antimony values from mixed metal sulfides, several are known for treating concentrates possessing relatively large amounts of arsenic values, including U.S. Pat. No. 3,709,680 to Holmes and Coltrinari, and U.S. Pat. No. 3,911,078 to Nadkarni et al. Holmes and Coltrinari disclose a process for removing arsenic from its ore concentrates by leaching the concentrates with an alkali metal sulfide to dissolve the arsenic values, precipitating the arsenic values from the solution by acidification, discarding the resultant arsenic values, and further treating the remaining solution in order to regenerate the alkali metal sulfide.
The Nadkarni reference discloses a process designed to remove essentially all of the arsenic from copper sulfide ores by leaching the concentrates with sodium sulfide in the presence of sodium hydroxide or other hydroxyl group in order to produce sodium thioarsenate and sodium thioantimonate. The arsenic values, along with any antimony present, are then crystallized from the solution and discarded, and the sodium sulfide/sodium hydroxide solution is then recirculated to the leaching step.
It is observed that the Nadkarni process is well suited for its purpose when dealing with sulfide ores containing arsenic in its pentavalent form. This highly oxidized form of arsenic produces sodium thioarsenate in accordance with the reactions presented in the reference, and this sodium thioarsenate may then be crystallized from solution. However, it has been observed that when antimony and arsenic are present in the initial concentrate in their trisulfide forms, the Nadkarni process is not as effective.
The process of the present invention separates antimony and arsenic from their concentrates, even when these values are in their trisulfide forms. Furthermore, in a preferred embodiment of the present process, a method is disclosed for the ultimate recovery of antimony.